The movie "Eight-year-old Dad" tells the story of Cao Luyi (Jin Shijia), a doctor in the ultrasound room of the Women's and Children's Hospital, who came to a welfare institution by accident and had to get along with a group of people with mental development disabilities. Doctor Cao Lu was at a loss from the beginning, and was gradually influenced by their innocence, simplicity and frankness, until he merged into the caring volunteer team represented by Wen Jing (Jiang Peiyao). Doctor Cao Lu witnessed the love between Liu Yingjun (played by Qiu Ze) and Wu Yanzi (played by Janine Zhang) with his own eyes, and welcomed a "miracle life" with them.